<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>计算税后实发工资</title>
    </head>
    <body>
        <input id="num1" placeholder="税前工资"/>
        <input type="button" value="计算实发工资" onclick="suanGongZi()"/>
        <input id="num2"/>
        <script type="text/javascript">
            function suanGongZi(){
                if(num1.value>3500){
                    num2.value=num1.value-((num1.value-3500)*0.2-555);
                }
                else{
                    alert("工资金额未达到缴税标准");
                }

            }

        </script>

    </body>
</html>